The apparently most advanced prior art method and apparatus fore extracting packing rings from a stuffing-box is the invention of Marsac et al described in U.S. Pat. No. 4,473,934, and known in the market place as a Hydraulic Packing Extraction Tool. The reader is directed to the Marsac et al patent as background of the industry and for an understanding of the environment of the present invention. With the Marsac tool, a high pressure water jet is discharged by a nozzle from about 1/2 inch to 3/4 inch above the packing rings to bore a hole in at least the first ring of packing rings in the stuffing box. This lessens the stress of the ring and the high pressure water, flowing through the hole, is pushed back by the next ring, and lifts the first ring out of the stuffing-box. Since the high pressure of the nozzle makes in a stationary relationship to the stuffing-box.
The Marsac et al process works well provided the packing is close to the top of the stuffing box. When extracting packing is deep stuffing boxes or the bottom rings from a standard box, the nozzle must be lowered well inside the stuffing box. When the packing rings start to move upward, they come in contact with the stationary nozzle tip which blocks the upward motion of that portion of the packing which has contacted the stationary nozzle. Those portions of the packing ring which are not in contact with the nozzle continue to be pushed upward by the water until the ring is canted within the stuffing-box. Once the ring is canted, the water escapes between the tilted edges of the ring and the box and the ring loses all pressure retention capabilities. This packing must now be extracted by hand. Resetting the nozzle higher will help because the ability to retain pressure under the packing has been lost.